Small ${\mathrm{Ni}}_m({\mathrm{C}}_{60}{)}_n$ clusters with $n+m<~4$ are studied using the tight-binding molecular-dynamics method generalized to treat heteronuclear systems. Our results confirm recent experimental deduction of the bonding behavior of Ni towards ${\mathrm{C}}_{60}.$ The direction of the charge transfer is found to depend on the geometry of the ${\mathrm{Ni}}_m({\mathrm{C}}_{60}{)}_n$ cluster. Furthermore, the present results reveal a striking dissimilarity in the bonding behavior between $\mathrm{Ni}-{\mathrm{C}}_{60}$ and Ni-graphite systems.

• Received 1 February 1999

DOI:https://doi.org/10.1103/PhysRevB.60.4521